Responders to Metronome-based Rhythmic Auditory Stimulation in Individuals Post-Stroke and Older Adults

Stroke is among the foremost causes of long-term disability worldwide. Though post-stroke neuromotor impairments are heterogeneous, they often result in reduced walking ability and physical activity, and a slow, asymmetric, and unstable gait. In the chronic phase of stroke, the persistence of walking impairment leads to subsequent declines in walking ability, setting off a cycle of disability and deconditioning, reduced mobility, and increased fall risk. The development and study of interventions that can improve walking ability after stroke has been identified as a top priority among patients, clinicians, and researchers, with the ultimate goal being the enhancement of independence and overall quality of life, and the mitigation of walking-related disability.

Stroke is a disease of aging, and older adults (OA) tend to walk more slowly and with a more variable walking pattern that is energetically more demanding. Similar to stroke survivors, the reduced function and quality of walking in older adults can lead to declines in walking ability, initiating a cycle of disability and deconditioning that increases the risk of injurious falls. Hence, maintaining walking function is crucial for preserving a high quality of life.

Rhythmic Auditory Stimulation (RAS) is a rehabilitation intervention that has shown promise for improving walking in both stroke survivors and older adults. Walking with RAS intervention has been proven to enhance walking function, particularly in terms of walking speed. RAS relies on the innate human capacity to synchronize movements with an external rhythm, such as walking to a regular auditory beat, a process referred to as auditory-motor entrainment. Rhythmic entrainment may stabilize gait patterns and reduce the metabolic cost of walking, as the body naturally selects a walking frequency that maximizes stability and minimizes energy expenditure. Moreover, rhythmic entrainment is thought to reduce the cognitive demand of walking, allowing individuals to allocate their attention to secondary tasks essential for safe community navigation. Despite the evidence supporting its effectiveness in improving walking speed and gait function, the biomechanical changes enabling these improvements are not well understood.

Furthermore, while RAS is an effective intervention, not everyone benefits from it equally. Individuals with stroke present with a wide variety of gait patterns, and the degree of gait impairment may influence the effectiveness of RAS intervention above and beyond any age-related changes. In this study, the investigators aim to identify predictors of the response to RAS intervention. More specifically, they seek to understand the association between baseline walking characteristics and the effect that RAS intervention has on walking ability.

For this analysis, the investigators define responders in three ways: (1) individuals who experience an increase in walking function, (2) individuals who see an improvement in gait quality, or (3) individuals who achieve enhancements in both gait quality and walking function while walking with personalized RAS.